Cutting elements having a pre-formed fracture plane for use in cutting tools

ABSTRACT

Cutting elements for cutting tools comprise a pre-formed fracture plane disposed in at least one surface of the cutting elements. The pre-formed fracture plane can comprise a groove cut into one of the surfaces of the cutting element, or the pre-formed fracture plane can be formed by using a laser or other heat concentrating source to weaken a portion of one of the surfaces of the cutting element so that the cutting element will break along the pre-formed fracture plane.

BACKGROUND

1. Field of Invention

The invention is directed to cutting elements or “cutters” for cuttingtools used to cut, abrade, or mill objects and, in particular, tocutting elements utilized in tools to cut objects within oil and gaswells, the cutting elements comprising a pre-formed fracture plane tofacilitate breakage of the cutting element along a pre-determinelocation of the cutting element so that the cutting element can eithercontinue to cut away an object in the wellbore, or so that the cuttingelement can be completely removed so that another cutting elementdisposed behind the fractured cutting element can begin cutting theobject.

2. Description of Art

In the drilling, completion, and workover of oil and gas wells, it iscommon to perform work downhole in the wellbore with a tool that hassome sort of cutting profile interfacing with a downhole structure.Examples would be milling a downhole metal object with a milling tool orcutting through a tubular with a cutting or milling tool. To facilitatethese operations, cutting elements are disposed on the downhole cuttingtool. In some instances, the cutting elements are stack one on top ofanother so that when the upper cutting element is worn or broken away,another cutting element can be exposed to the object in the well so thatcutting can continue.

SUMMARY OF INVENTION

Broadly, the invention is directed to a cutting element disposed on adownhole cutting tool utilized in cutting away an object disposed withinthe well, wherein the cutting element comprises at least one pre-formedfracture plane to facilitate breaking away a portion of the cuttingelement so that the cutting element can continue to cut or abrade theobject, or so that a second cutting element disposed behind the brokenaway cutting element can engage and cut the object. The term “object”encompasses any physical structure that is to be cut, abraded, or milledsuch as structures disposed within a well, for example, another toolthat is stuck within the well, a bridge plug, the well tubing, the wellcasing, or the like.

In one particular embodiment, the cutting elements are disposed onblades of a downhole cutting tool that are disposed on a face of thetool. The blades are disposed on the face such that rotation of the toolcauses rotation of the blades. In other embodiments, the cuttingelements are disposed on an end of a mill or other cutting tool.

In one embodiment of the cutting element, the cutting element comprisesa pre-formed fracture plane disposed on at least one surface of thecutting element. For example, in a specific embodiment the cuttingelement comprises a body having a cutting surface and a non-cuttingsurface wherein the non-cutting surface comprises a fracture planedisposed within the non-cutting surface. In one particular embodiment,the fracture plane comprises a groove cut into the non-cutting surface.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of one specific embodiment of a cuttingelement disclosed herein.

FIG. 2 is a front view of the cutting element of FIG. 1.

FIG. 3 is a first side view of the cutting element of FIG. 1.

FIG. 4 is a second side view of the cutting element of FIG. 1.

FIG. 5 is an enlarged side view of the view of the cutting element takenalong line 5 in FIG. 3.

FIG. 6 is an enlarged side view of the view of the cutting element takenalong line 6 in FIG. 3.

FIG. 7 is a bottom view of the cutting element of FIG. 1.

FIG. 8 is a side view of another specific embodiment of a cuttingelement disclosed herein.

While the invention will be described in connection with the preferredembodiments, it will be understood that it is not intended to limit theinvention to these embodiments. On the contrary, it is intended to coverall alternatives, modifications, and equivalents, as may be includedwithin the spirit and scope of the invention as defined by the appendedclaims.

DETAILED DESCRIPTION OF INVENTION

Referring now to FIGS. 1-7, cutting element 10 comprises top surface 20,front surface 30, bottom surface 40, first side or lateral surface 50,second side or lateral surface 60, and back surface 70. Top surface 20comprises cutting profile 22. As shown in the embodiment of FIGS. 1-7,cutting profile 22 comprises a plurality of segments 23 in which a backside 36 of one segment 23 is adjacent to and affixed to a front side 38of another segment 23. Back sides 36 and front sides 38 are referencedin FIG. 3. As shown in FIG. 6, cutting profile 22 of each segment 23comprises flat surface 24 having width 25, and angled surface 26disposed adjacent to flat surface 24 at angle 28. Cutting profile 22 ofeach segment 23 also includes vertical surface 27 which connects angledsurface 26 of one segment 23 to flat surface 24 of an adjacent segment23. In the embodiment shown in FIGS. 1-7, widths 25 of flat surfaces 24are in the range from approximately 0.005 inches to approximately 0.02inches and angle 28 is in the range from approximately 150 degrees toapproximately 175 degrees when based upon cutting element 10 havingoverall dimensions of a width and a length each in the range fromapproximately 0.3 inches to approximately 1 inch and a height in therange from approximately 0.2 inches to approximately 1 inch.

As shown in FIGS. 1-4 and 7, front surface 30 includes profile 32connecting front surface 30 with bottom surface 40. Profile 32 cancomprises a horizontal groove such as the bevel shown in the Figures, orprofile 32 can promise any other shape.

Disposed within bottom surface 40 is at least one groove 44 providingfracture plane 48. In the embodiment of FIGS. 1-7, cutting element 10comprises a plurality of grooves 44 providing fracture planes 48 betweenthe apexes 45 of grooves 44 and valleys 29 of cutting profile 22.Because grooves 44 are disposed horizontally across a width of cuttingelement 10, grooves 44 of FIGS. 1-7 are horizontal grooves. As shown inthe embodiment of the Figures, grooves 44 comprise angle 46 and depth47. Angle 46 may be in the range from approximately 40 degrees toapproximately 75 degrees and depth 47 may be in the range fromapproximately 0.01 inches to approximately 0.05 inches when based uponcutting element 10 having overall dimensions of a width and a lengtheach in the range from approximately 0.3 inches to approximately 1 inchand a height in the range from approximately 0.2 inches to approximately0.75 inches.

Although apexes 45 are shown disposed directly below valleys 29, it isto be understood that the apexes 45 can be moved slightly to the left orright of valleys 29 and still provide the fracture plane 48. Inaddition, although grooves 44 are shown is V-shaped grooves havingapexes 45, it is to be understood that grooves 44 can have any othershape, with or without apexes 45. For example, grooves 44 can comprise arounded shape, concave or convex curved walls with an apex, and thelike.

In the embodiment of FIGS. 1-7, first and second side surfaces 50, 60comprise grooves 54, 64, respectively which, as shown in this particularembodiment, intersect grooves 44. Grooves 54, 64 facilitate one segment23 breaking away from an adjacent segment 23 along fracture place 48.Although grooves 54, 64 can have any shape desired or necessary toassist breakage along fracture plane 48, as shown in the embodiment ofFIGS. 1-7, grooves 54 and 64 comprise bevels (best shown in FIG. 7)Because grooves 54, 64 shown in FIGS. 1-7 are disposed perpendicular tothe grooves 44, grooves 54, 64, these particular grooves 54, 64 arevertical grooves.

Although the dimensions of cutting element 10 can be modified as desiredor necessary to facilitate locating cutting element 10 on the cuttingtool to maximize the cutting ability of cutting element 10, in oneparticular embodiment, cutting element 10 comprises a width of 0.5inches, a length of 0.5 inches, a height of 0.25 inches, a segment widthof 0.07 inches, widths 25 measuring 0.1 inches, angle 28 measuring 166degrees, angle 46 measuring 60 degrees, and groove depth 47 measuring0.03 inches.

In operation, multiple cutting elements 10 are disposed on a cuttingtool, such as on the blade of a cutting mill or directly on the end ofthe cutting tool. The cutting element is then contacted with an objectto be cut, such as an object disposed within a wellbore. The cuttingtool is then rotated causing the cutting elements to bite into theobject and gradually cut, abrade, or mill away the object. During thecutting operations, one or more of the segments 23 of the cuttingelements may hinder the cutting operations such as by causing thecutting tool to jump off of the object, or because the cutting profilehas sufficiently worn down that the segment is no longer providingsufficient cutting action. In these situations, grooves 44 and, ifpresent grooves 54 and/or grooves 64, provide a weak point alongfracture plane 48 such that the cutting elements will break along aknown path, i.e., fracture plane 48. Upon breaking, one of the segments23 falls away while the remaining segment(s) continue to cut the objectin the well until the object is completely cut away or until all of thesegments break away from the cutting tool.

In certain embodiments, the cutting elements are stacked on top of oneanother so that when one cutting element completely breaks away, anothercutting element is exposed to the object so that cutting can continue.

In one embodiment, fracture plane 48 of the cutting element is formed bygrooves 44 that are disposed in bottom surface 40 by a laser or othersimilar device that melts and, thus, transforms, a portion of thematerial of the cutting element such that it is weaker than theremaining material forming the cutting element. Similarly, grooves 54,64 can be disposed within side walls 50, 60, respectively, using thismethod. This method of forming the cutting elements allows for thebottom, and if appropriate, side surfaces, to have grooves of weakermaterial to facilitate breakage along fracture plane 48. This method offorming the cutting elements also allows for the bottom and sidesurfaces 40, 50, 60 to lack sharp edges which can be broken or causedamage during installation on the cutting tool, yet still provide a weakpoint to facilitate breakage along fracture plane 48.

Referring now to FIG. 8, in still another embodiment, grooves 44 and, tothe extent present, grooves 54 (not shown), 64, of cutting element 110can be cut and then filled with a material 49 that is weaker than theremaining material forming the cutting element. This method of formingcutting element 110 also allows for the bottom surface 40, and ifappropriate, side surfaces 50 (not shown), 60, to have grooves 44, 54(not shown), 64, respectively filled with weaker material to facilitatebreakage along fracture plane 48 and for the bottom and side surfaces40, 50 (not shown), 60 to lack sharp edges which can be broken or causedamage during installation on the cutting tool, yet still provide a weakpoint to facilitate breakage along fracture plane 48.

It is to be understood that the invention is not limited to the exactdetails of construction, operation, exact materials, or embodimentsshown and described, as modifications and equivalents will be apparentto one skilled in the art. For example, fracture planes may also beincluded on the front and back surfaces of the cutting elements.Additionally, side grooves 54, 64 are not required to intersect valleys29 of cutting profile 22. Instead, grooves 54, 64 can stop prior toreaching valleys 29 of cutting profiles 22. Similarly, grooves 54, 64are not required to intersect grooves 44. Further, the grooves 54, 64are not required to be perpendicular with groove 44. Nor do grooves 54,64 need to be parallel to each other.

Moreover, grooves 44, and if present grooves 54, 64 can have any shapedesired or necessary to encourage breakage along fracture plane 48. Inaddition, the fracture planes do not have to be “flat” as shown in theFigures, but instead can be undulating or curved, and it is to beunderstood that upon breakage along the fracture plane the surface ofthe segments are not smooth, but will include burrs and the like.

Further, the cutting elements may be used on any type of cutting toolincluding but not limited to mill blades, drill bits, and non-blademills and may be included directly on the face of the cutting end of thetool. In addition, the angles of the fracture planes, cutting profile22, and profile 32, can be modified as desired or necessary tofacilitate placement of the cutting elements on the face or otherstructure carrying the cutting elements on the cutting end of thecutting tool or to facilitate cutting the object. Likewise, the shapesof the cutting elements can be modified as desired or necessary tofacilitate placement of the cutting elements on the face or otherstructure carrying the cutting elements on the cutting end of thecutting tool. And, the lengths, widths, and heights of the horizontaland vertical side surfaces can also be modified as desired or necessaryto facilitate placement of the cutting elements on the face or otherstructure carrying the cutting elements on the cutting end of thecutting tool or to facilitate cutting the object. In addition, theheight does not need to be consistent or constant across either thelength or width of the top surface or the length or width of the bottomsurface.

Further, the cutting profile can be modified as desired or necessary tofacilitate cutting the object. Moreover, the size and shape of thecutting surface portions on the top surface of the cutting elements canbe modified as desired or necessary to facilitate placement of thecutting elements on the face or other structure carrying the cuttingelements on the cutting end of the cutting tool or to facilitate cuttingthe object in the wellbore. Therefore, it is to be understood that theinvention is not limited to the exact details of construction,operation, exact materials, or embodiments shown and described, asmodifications and equivalents will be apparent to one skilled in theart. Accordingly, the invention is therefore to be limited only by thescope of the appended claims.

1. A cutting element comprising: a body comprising a cutting surfacehaving a cutting profile and a non-cutting surface, wherein thenon-cutting surface comprises a fracture plane disposed within thenon-cutting surface.
 2. The cutting element of claim 1, wherein thefracture plane is disposed substantially linearly below a valleydisposed in the cutting profile.
 3. The cutting element of claim 2,wherein the fracture plane comprises a groove.
 4. The cutting element ofclaim 3, wherein the groove comprises a V-shape.
 5. The cutting elementof claim 1, further comprising a plurality of fracture planes disposedwithin the non-cutting surface.
 6. The cutting element of claim 5,wherein each of the fracture planes is disposed substantially linearlybelow a respective valley disposed in the cutting profile.
 7. Thecutting element of claim 6, wherein the cutting surface comprises a topsurface and the non-cutting surface comprises a bottom surface disposedopposite the top surface, wherein the cutting element further comprisesat least three side surfaces disposed between the top surface and thebottom surface, and wherein at least one of the at least three sidesurfaces comprise a side surface fracture plane, the side surfacefracture plane being substantially perpendicular to at least one of theplurality of fracture planes disposed within the bottom surface.
 8. Thecutting element of claim 1, wherein the cutting surface comprises a topsurface and the non-cutting surface comprises a bottom surface disposedopposite the top surface, wherein the cutting element further comprisesa front surface, a back surface disposed opposite the front surface, afirst side surface, and a second side surface disposed opposite thefirst side surface, the front surface, back surface, first side surface,and second side surface being disposed between the top surface and thebottom surface, and wherein the first side surfaces comprises a sidesurface fracture plane, the side surface fracture plane beingsubstantially perpendicular to the fracture plane disposed within thebottom surface.
 9. A cutting element comprising: two or more segments,at least one of the two or more segments comprising a top cuttingprofile and a front side, the front side comprising a horizontal groovedisposed opposite the top cutting profile, the horizontal grooveproviding a fracture plane, wherein the two or more segments areinitially disposed adjacent and affixed to each other along the fractureplane, and wherein, after sufficient wear of one of the two or moresegments, one of the two or more segments breaks apart from theremaining one or more segments along the fracture plane.
 10. The cuttingelement of claim 9, wherein the fracture plane comprises an apex that isdisposed substantially linearly below a valley disposed in the topcutting profile.
 11. The cutting element of claim 10, wherein thehorizontal groove comprises a V-shape.
 12. The cutting element of claim9, the front side of at least one of the two or more segments comprisesa vertical groove disposed substantially perpendicular to and connectedto the horizontal groove.
 13. The cutting element of claim 9, whereinthe horizontal groove comprises a material disposed within thehorizontal groove, the material being weaker in strength as compared toa cutting element material forming the remainder of the one or moresegments.
 14. A cutting tool comprising: a body having a first end forconnection with a rotating component; and a cutting end for rotation inunison with the body, the cutting end comprising a cutting element, thecutting element comprising a cutting surface having a cutting profileand a non-cutting surface, wherein the non-cutting surface comprises afracture plane disposed within the non-cutting surface, wherein aftersufficient use of the cutting tool, the cutting element breaks along thefracture plane.
 15. The cutting element of claim 14, wherein thefracture plane is disposed substantially linearly below a valleydisposed in the cutting profile.
 16. The cutting element of claim 14,wherein the cutting surface comprises a top surface and the non-cuttingsurface comprises a bottom surface disposed opposite the top surface,wherein the cutting element further comprises at least three sidesurfaces disposed between the top surface and the bottom surface, andwherein at least one of the at least three side surfaces comprise a sidesurface fracture plane, the side surface fracture plane beingsubstantially perpendicular to the fracture plane disposed within thebottom surface.
 17. A method of cutting an object, the method comprisingthe steps of: (a) providing a cutting tool, the cutting tool comprisinga cutting element having a cutting surface and a non-cutting surface,wherein the non-cutting surface comprises a fracture plane disposedwithin the non-cutting surface wherein after sufficient use of thecutting tool, the cutting element breaks along the fracture plane; (b)contacting the cutting element with an object to be cut; (c) rotatingthe cutting element against the object; and (d) during step (c),breaking the cutting element along the fracture plane to remove aportion of the cutting element from the cutting tool.
 18. The method ofclaim 17, wherein the fracture plane is formed in the non-cuttingsurface by cutting a groove within the non-cutting surface.
 19. Themethod of claim 18, wherein the fracture plane is formed in thenon-cutting surface by heating a portion of the non-cutting surface witha laser.